A database that can be modelled through any other means apart from the traditional tabular relations is generally referred to as a NoSQL database. A NoSQL database organizes large distributed data sets into tuples - key value pairs and objects. NOSQL databases can be of different types –Graph Stores, Wide-Column Stores, Document Databases or Key Value stores. NoSQL -Not Only SQL implies that NoSQL databases do not adhere to any of the relational database concepts. NoSQL databases were developed to handle big data which relational databases were not capable of. NoSQL databases do not follow any strict schema. They distribute the database load on multiple hosts to scale out better.alue pairs and aggregates them to produce desired results. The input and output of the map and reduce jobs are stored in HDFS.